WARNING: partition mmcblk1p1 has no PARTNAME in its uevent file

tetherback v0.9.1
Found ADB version 1.0.41
Using default transfer method: adb exec-out pipe (--exec-out)
Device reports kernel 4.9.112-perf+
Device reports TWRP version 3.3.1-0
Reading partition map for mmcblk0 (62 partitions)...
partition map: 100%
Reading partition map for mmcblk0rpmb (0 partitions)...
partition map: 100%
Reading partition map for mmcblk1 (1 partitions)...
partition map: N/A% WARNING: partition mmcblk1p1 has no PARTNAME in its uevent file
Please report this issue at https://github.com/dlenski/tetherback/issues
Please post the entire output from tetherback!
partition map: 100%
Traceback (most recent call last):
File "/home/kurt/.local/bin/tetherback", line 11, in
load_entry_point('tetherback==0.9.1', 'console_scripts', 'tetherback')()
File "/home/kurt/.local/lib/python3.8/site-packages/tetherback/tetherback.py", line 317, in main
plan = plan_backup(args, partmap)
File "/home/kurt/.local/lib/python3.8/site-packages/tetherback/tetherback.py", line 190, in plan_backup
plan.update((p,BackupPlan('%s.%s.win'%(p, partmap[p].fstype), '-p')) for p in mp)
File "/home/kurt/.local/lib/python3.8/site-packages/tetherback/tetherback.py", line 190, in
plan.update((p,BackupPlan('%s.%s.win'%(p, partmap[p].fstype), '-p')) for p in mp)
KeyError: 'system'